The carnivore diet

This way of eating means avoiding plants and preferring only animal foods instead. Plants are considered to have a low bioavailability of nutrition for humans, and containing indigestible fiber, anti-nutrients, and high in sugar and low in healthy fats. Animal foods instead contain have high bioavailability of nutrition fo humans, no indigestible fiber, almost no anti-nutrients, and low in sugar and high in healthy fats. This is further improved if the animal ate its natural diet and had a good quality of life.

Phytochemicals are chemical compounds produced by plants, generally to help them thrive or thwart competitors, predators, or pathogens. Wikipedia
While foregut fermentation is generally considered more efficient, and monogastric animals cannot digest cellulose as efficiently as ruminants, hindgut fermentation allows animals to consume small amounts of low-quality forage all day long and thus survive in conditions where ruminants might not be able to obtain nutrition adequate for their needs. Hindgut fermenters are able to extract more nutrition out of small quantities of feed. The large hind-gut fermenters are bulk feeders: they ingest large quantities of low-nutrient food, which they process more rapidly than would be possible for a similarly sized foregut fermenter. The main food in that category is grass, and grassland grazers move over long distances to take advantage of the growth phases of grass in different regions. Wikipedia
Carbohydrates are compounds made up of types of sugar. Carbohydrates are classified according to their number of sugar units: monosaccharides (such as glucose and fructose), disaccharides (such as sucrose and lactose), oligosaccharides, and polysaccharides (such as starch, glycogen, and cellulose). Wikipedia